13-10 



metabolic rates, feeding activities, length of spawning or settlement 

 periods or various behavioral characteristics. Reflected changes in 

 benthic assemblages could include modified productivity, changed densi- 

 ties, addition or elimination of species, or more subtle shifts in 

 species composition. Although the direct effects of heat on marine 

 communities have received considerable attention from the public, they 

 have been shown in many cases to be one of the least objectionable 

 impacts of generating stations. In New Haven Harbor the low ratio of 

 plant cooling water flow to the volume of water moved with each tide, 

 the minimal harbor area experiencing heightened temperatures from the 

 discharge plume, and the lack of direct plume contact with the benthic 

 habitat, minimizes potential impact of plant operations on the benthos. 



Entrainment of planktonic larvae through station cooling sys- 

 tems often produces large mortalities (Enright, 1977) . Most of the domi- 

 nant benthic species in New Haven Harbor have planktonic larvae and are 

 therefore potentially subjected to losses from this impact. The net effect 

 of this impact is best inferred from recruitment patterns during appropri- 

 ate seasons. Another type of impact, impingement on the intake screens 

 may often be severe for populations of finfish and megabenthic inverte- 

 brates (large, motile forms such as lobsters and crabs) . Infaunal benthic 

 invertebrate species are generally not subject to impingement losses. 



EXPOSURE PANELS 



Seventy-five species and numerous higher taxa representative of 

 general hard- substrate benthic communities were identified from New 

 Haven Harbor exposure panels during the study. The long-term fouling 

 community was dominated by barnacles {Balanus spp.), hydroids {Obelia 

 longissima) , mussels {Mytilus edulis) , marine borers {Teredo navalis) , 

 mudworms (Polydora ligni) and tube-dwelling amphipods {Corophium insid- 

 iosum) . All dominants were consistently collected except Teredo navalis, 

 which disappeared from the harbor from 1976 through the study period, but 

 has been observed in July 1978 samples. Most taxa exhibited seasonal 

 fluctuations in abundance related to spawning and settlement. Long-term 



